#include <chrono>
#include <iostream>
int main() {
  using std::chrono::steady_clock;
  steady_clock::time_point t1 = steady_clock::now();
  std::cout << "等待一会...\n";
  steady_clock::time_point t2 = steady_clock::now();

  steady_clock::duration d = t2 - t1;
  if (d == steady_clock::duration::zero())
    std::cout << "流逝的时间为0\n";
  else
    std::cout << "内部流逝的单位时间数 " << d.count() << " periods.\n";
  std::cout << "系统能表达区间的 min: "
            << std::chrono::system_clock::duration::min().count() << "\n";
  std::cout << "系统能表达区间的 max: "
            << std::chrono::system_clock::duration::max().count() << "\n";
  return 0;
}
